1. Technical Field of the Invention
The present invention relates to a method of fabricating section bars, able to be articulated manually, usable as frames for walls, false walls, false ceilings and other architectural elements, and to the section bars obtained thereby.
2. Prior Art
Italian patent IT-A-1246940 describes a load-bearing section bar able to be articulated, usable as a contour and support to light structures, comprising a succession of open box elements. Each box element, obtained starting from a sheet metal band, is joined to the subsequent one by means of weakening areas obtained by drilling holes aligned transversely and by bending onto themselves band edges adjacent to said holes. In the band folds thus fabricated, opposed hinges are obtained whose axis is orthogonal with respect to the core of the section bar. Such hinges are normally known as plastic hinges, i.e. artefact areas wherein strong plastic deformations concentrate and wherein local deformation is allowed to grow without a corresponding increase in the bending moment.
Thus, the presence of these plastic hinges, though on one hand makes the section bar able to be articulated, on the other hand reduces its rigidity, so that, in order to be handled and transported, the section bar requires suitable stiffening elements.
In the second place, in order to have the required bending capability and meet installation requirements, it is necessary to increase the number of hinges per unit of section bar length, thereby increasing material wastage accordingly. The quantity of band required to manufacture a section bar capable of being articulated according to Italian patent IT-A-1246940 is inversely proportional to the size of the minimum bending radius allowed by the section bar.
From the point of view of construction such plastic hinges, as is evident, cause increased costs because, in addition to the intrinsic material wastage, they require a prolonged work process, particularly for that phase of longitudinal compression of the band in a state wherein it is already bent into a C shape. This phase also requires suitable tooling. The usage of the aforementioned section bar also entails some drawbacks, some of which are identified in the discussion that follows. Since the prior art section bar has multiple degrees of freedom for each hinged sector, the installer is forced preventively to stiffen it by screwing thereon a template or other tool that maintains it in the desired shape at least until the application of the covering plate that determines the structural collaboration between the support element, i.e. the section bar, and the borne element, i.e. a plate or the like, by means of fastening screws.
Indeed, because of its remarkable ability to be articulated, the prior art section bar can be used solely for curved parts.
Moreover, at the building site the section bar must necessarily be handled with its rigid packaging materials and thus with increased weight.
Additionally, the retrieval of building site residue forces the installer to reinsert the section bars not used in the construction process into the rigid packaging, with the deriving increase in the time needed to clear the site out and hence in costs for the construction firms.
Also, the presence of frequent empty areas constituted by the compacted hinges, makes very likely the possibility of screwing the fastening screws of the panels in such large and opposite areas, causing time wastage for the installer forced, in that case, to remove the screw placed in an empty area and to screw it again in a position where it meets the rigidity of the section bar.
Additionally, the presence of a great number of hinges taking up the inner space of the section bar makes it awkward to move the uprights. In addition to the section bar described above, there are other U-shaped section bars lacking plastic hinges, but provided with broad rectangular notches, obtained in the core and, in part in the wings of the section bar, or in the core and in one wing in order to render the section bar capable of being articulated. However this type gives no guarantee of suitable response, when installed, to the stresses deriving from its combination with the structural elements. Furthermore, DE-U-29619739 discloses a band of suitable plane material, in which a succession of weakening areas transverse with respect to the longitudinal axis of said band is obtained by shearing, but the deformation of its articulation section is difficult and requires hard manual efforts.
The object of the present invention therefore is to eliminate the drawbacks mentioned above of the section bars usable as frames for walls, false walls, false ceilings and other architectural elements, providing a method of fabricating a section bar that is rigid but able to be articulated manually at the moment of installation without having to use additional tooling.
In particular another object of the invention is to provide a method of fabricating a section bar as mentioned above which requires a reduced number of phases and without material wastage per unit of linear length.
Yet another object is to provide such a method of fabrication as to be applicable to all the shapes of section bars destined to be used in light prefabrication, in particular also to those section bars which, for the sake of working safety, present turned-back free edges or folded back edges due to functional requirements of hitching, fastening or the like. In its first aspect the invention, as it is characterised by the claims that follow, solves the problem of providing a method of fabricating rigid section bars able to be articulated manually, usable as frames for walls, false walls, false ceiling or other architectural elements section bars of the metal band type or made of other suitable plane material, formed with an open profile, fitted with a base or core and shaped as a C, a U, an xcexa9 or the like and provided at regular longlitudinal intervals with an articulation section, which from a general point of view, is characterised in that it comprises:
a first phase wherein, on a band of suitable material, a succession of areas of weakening transverse with respect to the longitudinal axis of said band is obtained by shearing, such weakening areas including polygonal slots whose axis of symmetry is transverse with respect to said longitudinal axis, alternatively upset with respect thereto, and further including lighteners obtained on transverse straight lines passing through vertices, chamfered with relatively wide fillets, of said polygonal slots; and
a second phase wherein said band is formed according to an open profile terminating, at its ends, with free edges.
In its second aspect the invention, as it is characterised by the claims that follows, solves the problem of providing a rigid section bar able to be articulated manually, usable as a frame for walls, false walls, false ceilings or other architectural elements, section bars of the type made with a metal band or other suitable plane material formed with an open profile, fitted with base or core and shaped in a C, a U, an xcexa9 or the like and provided at regular longitudinal intervals with an articulation section, which from the general point of view is characterised in that it comprises a band of suitable material, provided with a succession of areas of weakening transverse with respect to the longitudinal axis of said band, including polygonal slots whose axis of symmetry is transverse with respect to said longitudinal axis alternatively upset with respect thereto, and further provided with lighteners obtained on transverse straight lines passing through vertices, chamfered with relatively wide fillets, of said polygonal slots; said band, fitted with said slots and lighteners, being shaped according to an open profile terminating, at its ends, with free edges.
The advantages obtained through the present invention consist essential of:
making the performance of the profile, in essence the size of the minimum radius of curvature obtainable, independent from the quantity of material necessary to produce the section bar, unlike the section bar of the prior art patent mentioned above where the number of hinges provided per unit of length of the section bar, inversely proportional to the possible radius of curvature, conditions the weight of the section bar per unit of length;
allowing the production of a rigid section bar able to be articulated and thus to be shaped longitudinally on the building site or upon installation, easily and without requiring stiffening interventions;
minimizing the weight of the section bar to be transported and to be handled on the building site and the time required to retrieve building site residues;
making fabrication easier, with a reduced number of phases, and with the possibility of using the same tooling required for the fabrication of current section bars;
obtaining a section bar usable both for rectilinear and for curved lengths;
obtaining a section bar that, upon installation, reduces the frequency of invalid screw-ins in the connection with other constructive elements, such as plates or panels;
obtaining a section bar wherein the dimensions in its inner space are minimised, in order to ease the movement of the uprights.